1. Field of the Invention
This invention relates to a cooling system, and more particularly, it relates to a venturi used in a closed-loop cooling system to facilitate cooling a heat-generating component by raising the pressure of the fluid in the system and, therefore, the boiling point of the fluid, with the increased pressure establishing that there is flow in the closed-loop system.
2. Description of the Prior Art
In many prior art cooling systems, the fluid is absorbing heat from a heat-generating component. The fluid is conveyed to a heat exchanger, which dissipates the heat, and the fluid is then recirculated to the heat-generating component. The size of the heat exchanger is directly related to the amount of heat dissipation required. For example, in a typical X-ray system, an X-ray tube generates a tremendous amount of heat on the order of 1 KW to about 10 KW. The X-ray tube is typically cooled by a fluid that is pumped to a conventional heat exchanger where it is cooled and then pumped back to the heat-generating component.
In the past, if a flow rate of the fluid fell below a predetermined flow rate, the temperature of the fluid in the system would necessarily increase to the point where the fluid in the system would boil or until a limit control would turn the heat-generating component off. This boiling would sometimes cause cavitation in the pump.
The increase in temperature of the fluid could also result in the heat-generating component not being cooled to the desired level. This could either degrade or completely ruin the performance of the heat-generating component altogether.
In the typical system of the past, a flow switch was used to turn the system off when the flow rate of the fluid became too low. FIG. 6 is a schematic illustration of a venturi which will be used to describe a conventional manner of measuring the flow rate. Referring to FIG. 6, the velocity at point B is higher than at either of sections A, and the pressure (measured by the difference in level in the liquid in the two legs of the U-tube at B) is correspondingly lower.
Since the difference in pressure between B and A depends on the velocity, it must also depend on the quantity of fluid passing through the pipe per unit of time (flow rate in cubic feet/second equals cross-sectional area of pipe in ft2xc3x97 the velocity in ft./second). Consequently, the pressure difference provided a measure for the flow rate. In the gradually tapered portion of the pipe downstream of B, the velocity of the fluid is reduced and the pressure in the pipe restored to the value it had before passing through the construction. A pressure differential switch would be attached to the throat and an end of the venturi to generate a flow rate measurement. This measurement would then be used to start or shut the heat-generating component down.
In the past, a conventional pressure differential switch measured this pressure difference in order to provide a correlating measurement of the fluid flow rate in the system. The flow rate would then be used to control the operation of the heat- generating component, such as an X-ray tube.
Unfortunately, the pressure differential switch of the type used in these types of cooling systems of the past and described earlier herein are expensive and require additional care when coupling to the venturi. The pressure differential switches of the past were certainly more expensive than a conventional pressure switch which simply monitors a pressure at a given point in a conduit in the closed-loop system.
Another problem with the venturis of the past is that they were typically situated in line in a cooling system which caused the overall dimensions of the cooling system or portion thereof to increase because of the axial length of the venturi.
What is needed, therefore, is a system and method that facilitates using low-cost components, such as a non-differential pressure switch (rather than a differential pressure switch), which also provides a means for increasing pressure in the closed-loop system.
It is, therefore, a primary object of the invention to provide a system and method for improving cooling of a heat-generating component, such as an X-ray tube in an X-ray system.
Another object of the invention is to provide a closed-loop cooling system which uses a venturi and pressure switch combination, rather than a differential pressure switch, to facilitate controlling cooling of one or more components in the system.
Another object of the invention is to provide a closed-loop system having a venturi whose throat is set at a predetermined pressure, such as atmospheric pressure so that the venturi can provide means for controlling cooling of the heat-generating component in the system.
Still another object of the invention is to provide a circular venturi which reduces the overall axial length of the venturi by providing a venturi passageway which flows about the axis of the venturi.
In one aspect, the invention comprises a venturi having a first wall that lies in a first plane, said first wall comprising an outlet opening, a second wall that lies in a second plane substantially parallel to said first plane, a third wall situated between the first and second walls, the third wall lying in a third plane that is substantially perpendicular to the first plane, the third wall comprising an inlet opening and a throat opening; a fourth wall situated between the outlet opening and the third wall, the fourth wall having a first end secured to the third wall adjacent the inlet opening; the first, second, third and fourth walls cooperating to define a venturi passageway from the inlet opening, past the throat opening to the outlet opening.
Yet another aspect of this invention comprises a cooling system for cooling a component comprising a heat rejection component, a pump for pumping fluid to the heat-rejection component and the component, the pump comprising a venturi comprising a venturi inlet coupled to an outlet of the pump; the venturi comprising a first wall that lies in a first plane, the first wall comprising the venturi outlet, a second wall that lies in a second plane substantially parallel to the first plane, a third wall situated between the first and second walls, the third wall lying in a third plane that is substantially perpendicular to the first plane, the third wall comprising an inlet opening and a throat opening, a fourth wall situated between the venturi outlet and the third wall, the fourth wall having a first end secured to the third wall adjacent the inlet opening; the first, second, third and fourth walls cooperating to define a venturi passageway from the venturi inlet, past the throat opening to the venturi outlet opening, a conduit for communicating fluid among at least the component, the heat-rejection component and the pump.
Still another aspect of this invention comprises an x-ray system comprising an x-ray apparatus for generating x-rays, the x-ray apparatus comprising an x-ray tube situated in an x-ray tube casing and a cooling system for cooling the x-ray tube; the cooling system comprising a heat-rejection component coupled to the x-ray tube casing, a pump for pumping fluid to the heat-rejection component and the component; the pump comprising a conduit comprising a venturi having a predetermined pressure applied at a throat of the venturi, a conduit for communicating fluid among the x-ray tube casing, the heat-rejection component and the pump, the venturi comprising a first wall that lies in a first plane, the first wall comprising a venturi outlet, a second wall that lies in a second plane substantially parallel to the first plane, a third wall that lies in a third plane between the first and second walls, the third plane being generally circular and substantially perpendicular to the first and second planes, the third wall comprising an inlet opening and a throat opening, a fourth wall situated between the venturi outlet and the third wall, the fourth wall having a first end secured to said third wall adjacent the inlet opening, the first, second, third and fourth walls cooperating to define a venturi passageway from the venturi inlet, past the throat opening to the venturi outlet.
Yet another aspect of this invention comprises a venturi comprising a substantially planar first wall having a venturi outlet opening, a second wall coupled to the first wall and defining a cylindrical area, the second wall comprising a venturi inlet opening and a throat opening, a third wall situated within the cylindrical area and coupled to the substantially planar first wall in opposed relation to the second wall, the third wall comprising a first end coupled to the first wall adjacent the inlet opening, the substantially planar first wall, the second wall and the third wall cooperating with a fourth wall to define a passageway in communication with the venturi inlet opening, an outlet area at the venturi outlet area and a throat area adjacent the throat opening to define a predetermined pressure.
Yet another aspect of this invention comprises method for cooling a component situated in a system, the method comprising the steps of coupling a component to a pump for pumping a cooling fluid through heat-rejection component, pumping the cooling fluid through a circular venturi having a throat opening subject to a predetermined pressure, and increasing a boiling point of the cooling fluid, thereby increasing an operating temperature of the X-ray system.
Yet another aspect of this invention comprises a pump for pumping fluid comprising a pump motor comprising an axis, a circular venturi coupled to an outlet end of the pump, the circular venturi defining a venturi passageway that flows in a plane about the axis.
These and other objects and advantages of the invention will be apparent from the following description, the appended claims, and the accompanying drawings.